Radicalized U.S. residents willing to carry out attacks with “little or no warning” have helped create one of the biggest terrorist threats in years, Homeland Security Secretary Janet Napolitano said today.

“The terrorist threat to the homeland is in many ways at its most heightened state since 9/11,” she said in prepared testimony for a hearing of the House Homeland Security Committee in Washington.

Al-Qaeda affiliates and allies increasingly are trying to recruit Westerners or those with ties to the U.S. and Europe, Napolitano said. The recruits include Pakistani immigrant Faisal Shahzad, who tried to set off a bomb in New York’s Times Square in May, she said.